When the item "The Core of the Claw" is in your pocket, you may use this skill. The item "Core of the Claw" can be obtained from Swinedimples Academy after completing quest #075 (Rake a Tail Feather) and quest #076 (Talonted Trio).
How to get this item:
After you have beaten the Dreadmaster, go to the first floor of the academy and go to the far right to find a NPC named Klaus. You must have 30 Claw Skill Points to continute. After you have beaten #075 Rake a Tail Feather, you will have to do another quest, quest #076, requiring you to defeat three apprentices (monsters) to obtain Hand of God.
The monsters you must defeat:
1st: Tearwolf (Snowberian Coast)
2nd: Claws (Oubliette)
3rd: King Crab (Ocean, around edges)
After that, return to Swinedimples, talk to Klaus and obtain Core of the Claw, put it in your pocket and you can now use Hand of God.
Game description: "Unholy attack that flays foes' flesh from their bones."
This skill uses 14 MP.
Note: Your Claws skill must be 100 to obtain this quest and you must have Claw equipped to use this ability. Damage is calculated solely through Strength.